In the hair cutting art it has been well known to provide hair clippers with means for adjusting or controlling the height of cut or the length of hair remaining after cutting with a hair clipper. In these prior art devices the comb or stationary blade is conventionally adjustable with respect to the cutter or movable blade so that the tips of the teeth on the cutter engage the comb teeth at a different location depending on whether it is desired to cut the hair short or long. Examples of such adjustment means are included in the U.S. Pat. Nos. to Wahl, 1,895,183; Andis, 2,869,234; and Bender et al, 3,531,862.
The comb teeth are designed to taper so that the teeth are thickest at the base and tapered to a point. When the cutter is adjusted so that the tips of the cutter teeth are in substantial alignment with the tips of the comb teeth, the shortest possible cut is obtained. As the cutter is retracted and the tips of the cutter teeth are moved toward the base of the comb teeth, the length of the hair remaining after the cutting is progressively longer.
It has also been known in the prior art to provide supplementary guards or attachments which are similarly used to control the length to which the hair is cut. Examples of such prior art are Waldron U.S. Pat. No. 2,229,688, and Malone, U.S. Pat. No. 2,716,809.
A somewhat different type of guard which limits the amount of engagement between the blade set and the hair is shown in Groves U.S. Pat. Nos. 2,867,902 and 3,651,570. The '570 Groves patent includes a frame 16 which is adjustably mounted on a hair clipper in a manner so that the teeth of the blade set are exposed through an opening 20 in the guard. Suitable adjustment of this guard can prevent an undesirable penetration of the clipper teeth into the hair when the hair is being cut by an amateur or by one using the hair clipper on himself. This type of undesirable penetration by a hair clipper is often referred to as gouging.
It has also been known in the prior art to utilize razor blades in connection with combs for the purpose of thinning hair. In some of these devices the blades have been made adjustable to control the operation of the blade in thinning the hair. Examples of these razor blade type hair thinning devices are shown in Grachan U.S. Pat. No. 2,252,628 and Szabo U.S. Pat. No. 3,183,589.
Another somewhat unusual type of clipper having adjustment means to regulate the amount of hair cut is shown in Carter U.S. Pat. No. 2,470,287. The Carter patent provides adjustment of the comb so that the cutter effectively engages either one of two sets of teeth. In the advanced position of the comb, the cutter teeth will overlap the deeper comb gullets while not overlapping the shallower comb gullets. This arrangement will vary considerably the amount of hair cut by the blade set.
All of the devices exemplified by the prior art patents illustrate means for varying the action of a hair clipper blade set in cutting hair. With the exception perhaps of the Groves patent, however, none of these devices provides an electric hair clipper which would be suitable for one's use in thinning, cutting, or grooming one's own hair. The principal difficulties involved in cutting one's own hair is the fact that one cannot properly observe the hair being cut and the fact that the hands and arms are so contorted to apply the hair clipper to the top, back, or sides of the head that all dexterity is virtually lost and gouging of the hair results.
With our present day hairstyles for men, it is well accepted to have considerably longer hair than was considered proper only a few years ago. It is no longer considered necessary for a man to visit his barber once a week or once every two weeks to have his hair carefully edged and trimmed to give it a uniform appearance with the length increasing gradually from the very short hair on the neckline up the back and sides to the longer hair on the top. This so-called shingled or tapered effect which used to be required in a well-groomed head of hair is no longer considered necessary. Accordingly, the requirements for a hair clipper which would be usable to cut one's own hair has changed considerably. It would be desirable, however, to have a hair clipper which would effectively trim and thin hair between hair cuts to permit a man to still look neat even though he only has his hair cut once every few months.